He said the EU is ready to "step up" financial aid for implementing EU laws, to "top up" International Monetary Fund loans, and to "help bring on board other international partners," such as the World Bank, if Ukraine says Yes.

He noted that "the … backdrop for our efforts is the looming financial crisis in Ukraine."

He did not give figures, but he added that EU aid "will only get bigger and bigger" after the treaty is signed.

For his part, Arbuzov said pro-EU protesters in Kiev should not expect good news any time soon.

He noted the EU and Ukraine must first create a new "working group," draft an agenda for its meetings and negotiate a "roadmap" for implementing the EU treaty.

"We cannot tell the date … both sides have a lot of issues to talk about," he added.

The Arbuzov visit comes after Ukrainian President Viktor Yanukovych said No to the pact in November, citing Russian pressure.

It also comes amid mass-scale anti-Yanukovych rallies and police crackdowns.

In the run-up to Yanukovych's u-turn, EU countries quietly agreed to sign the text even if he did not fulfil their criteria: reforming electoral laws; reforming the judiciary; and freeing former PM Yulia Tymoshenko from jail.

But despite Fuele's offer, the moment of good will has evaporated.

Asked by EUobserver also on Thursday what happened to the criteria, Poland's ambassador to the EU's Political and Security Committee, Pawel Herczynski, said: "This EU position remains in force. Support from the EU is not unconditional. It is conditional."

Meanwhile, the crackdowns have added extra items to the list.

Fuele told Arbuzov he must free demonstrators arrested in recent days and bring to justice policemen who used excessive force.

Herczynski told this website Yanukovych must hold a "roundtable" with opposition leaders.

Another EU diplomat warned that some EU countries might no longer be willing to sign even if Yanukovych bends over backwards.

Looking ahead to a meeting of EU foreign ministers in Brussels on Monday, the EU diplomat said: "Without a new orientation debate on Ukraine, we cannot go ahead. There needs to be a new decision by the [EU] Council and these past two weeks might have changed the minds of some member states."

If the EU says No, there will be one happy man at Monday's meeting: Russian foreign minister Sergei Lavrov.

The EU ministers invited him to lunch before the Ukraine crisis erupted.

He is due to talk about Iran, the Middle East Peace Process, Syria, and the EU-Russia summit in January. But he is also likely to get an ear-bashing on Russia's threats to bankrupt Ukraine.

Russia's actions are "unacceptable," Herczynski said.

If the EU ends up saying No, it might also make Yanukovych happy.

Ukrainian opposition chiefs, such as Vitali Klitschko, told Fuele on Thursday that the President does not want to sign and that the new "roadmap" is a ruse to buy time to dismantle protests.

The collapse of the EU deal and a financial crisis in Ukraine might also make Yanukovych, and Arbuzov, rich.

Arbuzov is part of a Yanukovych clan, known in Ukraine as the "Familia" - the deputy PM's mother is the CEO of a bank owned by Yanukovych's son.

"Why would any government pursue such a harmful and mindless economic policy? The simple answer is that it benefits the ruling 'family' and its closest friends," he said.

"Previously unknown individuals, who are presumed to be connected with people at the top, have taken over a large number of private companies at low prices. The worse the economic situation is, the cheaper Ukrainian companies become for these selected buyers," he added.